The invention relates to a fuel tank for vehicles having a filler tube and having a filling level limiting device, with the filler tube comprising, in the interior of the fuel tank, a closing device which interacts with an actuating device. The filling level limiting device is intended to ensure that the filling device shuts down in the event of a build-up of a counter pressure, and to thereby prevent overfilling of the fuel tank. In the presence of a ventilation system, the build up of a sufficient counter pressure is not ensured and it is imperatively necessary to prevent an infiltration of fuel into the activated carbon filter as a result of overfilling.
In conventional fuel tanks, as a filling level limiting device, provision is made of a float which is directly coupled to a flap in the filler pipe. This is unsatisfactory since the float closes the flap to the extent to which the liquid level in the tank rises, and since the liquid level is unsettled during the tank filling process. This may result in the flap briefly opening again after closing, and thereby delaying the shutdown. Furthermore, such systems may only be used if the filler tube opens out into the tank at the height of the filling level.
U.S. Pat. No. 5,950,692 discloses a filling level limiting device in which the float is connected via a lost motion device to a flap which closes in the flow direction. In this way, the flap remains fully open during the filling process and closes abruptly when the nominal filling level is reached. The lost motion is also intended to prevent the flap opening again in the event of a fluctuation of the filling level once it has closed. That and the degree of sealing of the flap is however determined, in the limited range of the lost motion, only by the pressure upstream of the flap, and is therefore unreliable. The abrupt closure of the flap leads to a massive overflow outward during a tank filling process with a fully open filling nozzle. Additional damping would further increase the risk of the flap not opening as the liquid level falls.
It is therefore the object of the invention to create a filling level limiting device which closes quickly, but not abruptly, precisely when the nominal filling level is reached, and then reliably does not open again even under intense fluctuation of the liquid level. It is occasionally also desirable for the closing device to be actuated by remote control and to permit re-filling of the tank even after a small amount of fuel has been extracted.